System of electrical distribution.



J. L. WOODBRIDGB.

SYSTEM OI ELECTRICAL DISTRIBUTION.

APPLICATION rum) nov.1o, 1909.

1,058,832. Patented Apr. 15,1913.

Illmllllllli:

W/TNESSES: llWE/WM i165: ALWJ a mu 5/ m a 0' 75ml JOSEPH L. WOODBRIDGE,OF PHILADELPHIA, PENIISYLVANIA.

SYSTEM OF ELECTRICAL DISTRIBUTION.

Specification of Letters Patent.

Patented Apr. 15, 191-3.

Application filed November 10, 1909. Serial No. 527,225.

To all whom it may camera:

Be it known that I, J OSEPH LESTER Woon- I RIDGE, a citizen of theUnited States, and

a resident of Philadelphia, in the county of "l 'hiladelphia and Stateof Pennsylvania,

;;hi'y invented a certain new and useful Sysg-iztem of ElectricalDistribution, of which the following is a specification.

K "This invention comprises means for controlling the speed of anelectric motor. It is particularly applicable to the control of anelectric motor arranged to control the operation of storage batteryregulating apparatus such as is shown and described in Patent #895,760issued to Robert C. Hull on August 11th, 1908, and in Patent #895,825issued to me on August 11th, 1908. The systems of electricaldistributiondisclosed in the patents above cited-include storage battery regulatingapparatus re sponsive to departures from any predetermined average loadon the generators and include a motor arranged to control saidregulating apparatus so as to slowly vary the load on the generators,this motor being responsive to departures from some pre determinedcondition of the battery circuit. In such a system of electricaldistribution it is frequently found desirable that the motor shouldattain its maximum speed upon a slight departure from the predeterminedcondition of the battery circuit and should maintain this speedpractically constant for all greater departures from such predeterminedcondition. For exam le, if a sudden increase of load occurs on t econsumption circuit and the regulating apparatus is arranged to transferthis load immediately to the attery and then slowly from the battery tothe generators, it may be desirable to effect this transfer from thebattery to the generators as rapidly as permissible without disturbingthe operation of the latter, whether the load fluctuation be small orgreat. In the present invention I provide means for controlling themotor which produces this transfer in such a way as to bring about thisresult. i Broadly, the invention includes means for applying to he motoran artificial load which is practically zero at the start and remainsnegli ible below a certain speed, while beyond t at point it increasesrapidly for small increase of speed. I also provide, in circuit with themotor armature or field winding (whichever is made responsive to theelectrical condition of the battery cit cuit) controlling means forlimiting theflow of current 'i'n'said armature or field circuit, thuslimitin the motor torque notwith standing a cons1 erable rise of thevoltage applied to the circuit which includes this armature or fieldwinding. It wilh be under stood that while I have shown anddescribedbelow the application of this invention to battery controllingapparatus, the invention itself 1s not-in any we limitedto this clam ofapparatus, and it Will be obvious that the invention may be applied tothe control of motor speed for many other purposes.

M. invention will be more clearly understoo by reference to theaccompanying diagrams, in which--- Figure 1 shows one embodiment of theinvention in which themotor armature is made responsive to theelectrical condition of the battery circuit, while Fig. 2, shows amodification in which the motor field is made so responsive.

Referring to Fig. 1, G is a generator supplying current to the circuit1-2 to which are connected translating devices L constituting afluctuating load. Across the circuit 12 is connected the storage batteryB with its booster D, the field F of the latter being controlled in theusual manner by the carbon regulator C, responsive by means of thesolenoid S, connected into the conductor 1, to small fluctuations ofload on the generator G. The average current on the generator, passingthrough the solenoid S,

is balanced by the tension of the spring Q spring. The motor M isprovided with afield windingF" which in thiscase is conat the other endof the lever of the oarnected directly across the circuit'1-2 in serieswith the rheostat R. For any setting'of this rheostat a constantexcitation is supplied to the field oi the motor. The armature of themotor is connected by means of conductors 3 and 4 across the terminalsof the booster D. The adjustment is such that when the voltage of thebooster D is zero the battery is neither charging nor since the voltageapplied to its armature till is zero. Any variation of booster voltagefrom the zero point will cause the battery to charge or discharge and atthe same time will send current through the armature of the motor M,which will rotate it in the direction to change the tension on thespring Q and bring the voltage of the booster gradually back to zero,thus transferring the fluctuation of load from the battery to thegenerator. As described in the patents cited above this eflect isproduced slowly so that the battery takes the quick fluctuations of loadand the generator load follows the slow changes in the average demand.

Mechanically connected to the motor M is shown a damping deviceconsisting of a corrducting disk-E mounted on the shaft of the motor androtated between the poles of an electro-magnet H. This electro-magnet isexcited by a coil ll connected across the conductors 3 i,-and thereforein parallel with the armature of the motor M. This magnet 'is providedwith a magnetic shunt T, of

comparatively small cross-section, connected across the magnetic circuitin parallel with the air gap 5 in which the disk E revolves. Themagnetic circuit is also interrupted by a gap of non-magnetic material Kso located that all the magnetic lines produced by the exciting coil llmust pass across this gap and then sub-divided between the magneticshunt T and the air gap J. In series with the coil l 'is a rheostat Rwhich serves to adjust the action of the coil l and determine the speedof the motor M. Tu series with conductor a is a resistance N of hi htemperature co-eficient, such for examp e, as the well known hot wireresistances which have the property or increasing rapidly in resistanceat a certain critical point with very small changes of current therebymaintaining substantially constant current in the circuit with widevariations of applied voltage, after said voltage exceeds a certainpoint.

The operation or this apparatus will then be as follows: With zerovoltage across the booster D the armature of the motorM will receive nocurrent and will remain at rest. A small voltage in the booster D willsend current through the armature of the motor -M by way of conductors 3and i and will start the motor. The resistance of the-coil l is-large ascompared with that of the an mature winding of the motor and the coil llwill therefore divert but little current from the armature at lowbooster voltages. This small current in the coil 1 will produce somemechanism in the magnet H but practically the air J. have sheet upon themotor. The torque required to start the motor will be somewhat greaterthan that required to keep it in motion after it is once started, itsload being principally friction. Once started the motor will thereforecontinue to increase in speed until its counter electro-motive-force hasrisen sutliciently to reduce the current in its armature to the point ofequilibrium and it will continue to run at this speed so long as thevoltage of the booster l) is constant. As the voltage of the boosterincreases there will be a tendency to increase the speed of the motorcorrespondingly.

, The increase of voltage applied to the coil I will however soonsaturate the magnetic shunt T and force magnetic lines across theair-gap J; This will .produce a retarding action on the disk E, callingfor increased current in the motor armature in order to carry its load.This increase of current will produce an increasing drop in theresistance N which will reduce the voltage applied to the armatureterminals of the motor'and prevent its speed from rising. Thecharacteristic of the resistance N may be so chosen that at acomparatively low. voltage across this resistance it will reach itscritical point beyond which the current which it will transmit remainspractically constant for a comparatively wide variation of voltage. Solong as this current is held constant the speed of the motor must.remain constant since any increase in speed would increase the retardingefiect ot the disk E and call for additional current in the motorarmature to produce the additional torque required.

In Fig. 2; is shown a modification of the apparatus included in F ig. llIn this figure the armature of the motor M is connected across theconductors l2 in series with the rheostat R The apparatus may be .sodesigned that the counter elective-motiveforce of the motor M is alwayssmall as compared with the voltage across the circuit l--2, so that thecurrent passing through the rheostat R willibe substantiallyconstant andindependent of the counter electro-motive-torce of the motor. The fieldF of the motor is connected across the booster 1] of apparatus will besimilar to those obtained horn the arrangement shown in Fig. 1. Whenbooster voltage is zero the flow through the field coil F and the motormotorM will be at rest as it will have no field excitation As soon asasmall voltage is developed In the booster-D, current W111 the coil; Iwill produce asuiflicientreduction crease in the fieldstrength oft emotor will parallel in the motor-torque and a suliicient retard.- nge'flect in the" disk E to prevent further mcrease 01f If the voltage ofthe booster increases beyond this int the inincrease 'the:,-torque ofthe motor and at-the same time increase the counter elect-ro-mo-.tiveforce even with no increase of speed. This increase, of counter,electro-moti'veforce" will divert more of the-total current passingthrough R from the armature through the coil I thus reducing the motortorque to some extent, and at the same time further increasing theretarding action of the disk. E. .-By properly designing theap-- paratusthis latter effect may be made to balance the effect due to theincreasein the field strength and the speed may beheld constantregardless of the increase of voltage'of the booster. The efiect of'theresistance N, which has a high temperature coeflicientas described inconnection with Fig. 1, will limit the increase of current in fieldwinding F after the voltage of the booster has reachedia certain pointand therefore assist in maintaining constant motor'speed regardless ofvariations in the booster voltage.

It will be-understood that modifications may be made in the details ofthe apparatus without departing from the spirit of the invention,

WhatI claim therefore, and desire to secure-by Letters Patent is- 1. Incombination a source of constant potential, a source of varyin' electricmotor provided wit ;a field wind and an armature winding," means fortransmitting currentto' one of said windings from' the constantpotential source, a conducting circuit from the other of said windingsto the source 'of varying potential, a m etic braking device for themotor, an exciting coil for said'device connected in with the motorarmature, and a resistance for limiting the total current supplied tothe armature and exciting coil.

2. In combination a source of constant po-- tential, a source of varyingotential, an electric motor provided with a eld winding and an armaturewinding, means including a resistance for transmitting current to thearmature winding fromtheponstant potential source, a. conducting circuitfrom the potential, an

field winding to the source of varying potential, a device in the lastnamed circuit adapted to limit the current variations therein, amagnetic braking device for the motor, and an exciting coil forthebraking device connected in parallel with the motor armature,'exclusiveof the resistance. 7

3. In combination a consumption circuit and its source, a storagebattery operatively arranged to deliver and receive energy to and fromthe circuit, regulating apparatus for controlling the charge anddischarge of the battery in response to departures from a predeterminedelectrical condition of the circuit, a motor for controlling saidapparatus with respect to the predetermined condition to ,departuresfrom which it is re sponsive,'said motor provided with an armaturewinding and a field winding, means for connecting one of said windingsinto a sub stantially constant current circuit, a connecting circuit forsupplying current to the other -windin responsive to the electricalcondition of t e battery circuit, and a device for limiting the currentin said connecting circuit whereby: the speed of the motor is limited.

4. In combination a consumption circuit and its source, a storagebattery operatively arran d to deliver and receive ener' 'vto and fromthe circuit, regulating a paratus for controlling the charge and discarge of I the battery in res onse to departures from a predetermined eectrical condition of the circuit, a motor for controlling saidapparatus with respect to the predetermined condi- 1 tion to departuresfrom which it is responsive, said motor provided with an armaturewinding and afield winding, means for connectin one of said windingsinto asu stantia ly constant current circuit, a connecting circuit forsupplying current to the other winding responsive to the electricalcondition of the battery circuit, a device for limiting the current insaid connecting circuit, and insane for applying to the motor a loadindependent of the regulatingl apwit paratus and adapted to increasecrease of motor speed whereby said speedis limited.

5. In combination two sources-of electrical energy connected in parallelrelation, apparatus ferco'ntrolling the (l1V1S10I\ 0f load between themincluding a motor having field and armature windings, anelectro-magnetlc brake for the motor, a circuit including the fieldwinding of said motor, another circuit including in parallel relationthe armature winding and the exciting" coiloftheelectromagnetic brake,means for transmitting a substantially constant current to one of saidcircuits and means for connecting the other to respondto variations ofelectrical condition of one of the sources.

6. In combination two sources of electrical lot energy connected inparallel relation, apparatus for controlling the division of loadbetween them including a motor having field and armature windings, anele'ctro-magnetic brake for the motor, a circuit including the fieldwinding of said motor, ZLDOt'llGf'ClIClllt including in parallelrelation the armature winding and the exciting coil for theelectromagnetic brake, means for transmitting a substantially constantcurrent to one of said circuits and means for connecting the other torespond to variations of electrical condition of one of the sources anda device in the last named circuit for limiting the current therein. j

7 In combination a storage battery, means for controlling its charge anddischarge, an electric motor for automatically adjusting saidcontrolling means, an electro-magnetic brake for said motor including amagnetic circuit consisting of a main magnetic path completed by twomagnetic paths in parallel relation whereof one has a smaller crosssection than the main path, While the other is interrupted by anon-magnetic gap, a conducting body revoluble by the motor in said gap,a secondnon-magnetlc gap in the main path and an exciting 0011 for saidmain path.

8. In combination a storage battery, means for controlling its chargeand discharge, an

electric motor for automatically adjusting said controlling means, anelectro-magnetlc brake for said motor including a magnetic circuitconsisting of a main magnetic path completed by two magnetic paths inparallel relation whereof one has a smaller cross section than the mainpath, while the other is interrupted by a non-magnetic gap, a conductingbody revolubleby the motor in sa d gap, a second non-magnetic gap in themain path and an exciting coll for sald main path connected in parallelwith the'motor armature.

9.- In combination a constant potential consumption circuit, two sourcesof electrical energy connected thereto, apparatus for con- -trolling thedivision of loadbetween them including a motor having field and armaturewindings, an electro-magnetic brake for the motor, a circuit includingthe field winding of said motor, another circuit including in parallelrelation the armature winding and the exciting coil for theelectromagnetic .brake, means for transmitting current from theconsumption circuittd one of said circuits, and means for connecting theother to respond tovariations of electricaljccndition of one of thesources.

10. In a system'of electrical distribution including 'a storage battery,apparatus for controlling its charge and discharge, an

increasing with increase of motor speed,

whereby said increase of speed is checked abruptly at a predeterminedpoint.

j 11. In combination with field controlling ap aratus an electric motorfor varying the adjustment or said apparatus having a field winding andan armature winding, independent circuit connections for the twowindings, a resistance in series with the armature winding and a branchcircuit in parallel relation with the armature winding exclusive ofsaid" resistance for increasingly diverting current therefrom uponincrease of armature counter-electro-motive-force.

12. In combination with field controlling apparatus, an electric motorfor varying the adjustment of said apparatus having a field winding andan armature winding, inde ndent circuit connections for the two winings, a resistance in series with the armature winding, a branch circuitin parallel with the armature winding exclusive of said resistance forincreasingly diverting current therefrom upon increase of armaturecounter-electromotive-force, and means for applying an artificial. loadto the motor.

13. In combination two sources of electrical energy connected inparallel relation, field regulating apparatus for controlling thedivision or load between them, an electric motor for varying theadjustment of said apparatus having a field winding and an armaturewinding, means for connecting one of said windings to respond to changesof electrical condition or one of said sources, circuit connections fortransmitting current to the other of said windings, a resistance inseries with the armature winding, and a branch circuit vin parallel withthe armature winding exclusive of said resistancefor increasinglydiverting current therefrom u on increase of armature counterelectro-motiveforce.

14. .In combination two sources of electrical energy connected inparallel relation,

increase of speed is checked abruptly at a predetermined point.

15. In combination two sources of electrical energy connected inparallel relation, field regulating apparatus for controlling thedivision of load between them, and electric motor for varying theadjustment of said apparatus having a field winding and an armaturewinding, means including a resistance of high temperature co-efficientfor connecting one of said windings to respond to changes of electricalcondition of one of the sources, separate circuit connections fortransmitting current to'the other of said windings, a branch circuit inparallel with the armature winding for increasingly diverting currentfrom said winding upon increase of armature counter-electro-motiveforce,and means for applying to the motor a load independent of the regulatingapparatus.

16* In a system of electrical distribution including an electriccircuit, regulating apparatus in operative relation thereto, a motor forcontrolling said regulating apparatus having a field winding and anarmature win'ding, means for transmitting uni-directional currentthrough one of said windings, and connections for transmitting throughthe other winding current varying in amount and direction in response tochanges in the electrical condition of the circuit, the combination of adevice connected in series with the latter winding and'adapted to in-

